Nucleic Acids

DNA (deoxyribonucleic acid) is the largest molecule in the human body. DNA is made up of 2 complimentary strands of nucleotides. Nucleotides are composed of 3 sub-molecules: pentose sugar, a phosphate, and a nitrogen base (purine/pyrimidine).I'll go into more detail about nitrogen bases later on, lets go back to DNA for now. The 2 complimentary strands are joined by hydrogen bonds. Adenine bonds with thymine with 2 hydrogen bonds, and cytosine attaches to guanine with 3 hydrogen bonds. These nitrogen bases hold together the sugar-phosphate backbone of the DNA. This is what allows it to spiral and fold into the unmistakeable double helix, known as DNA.

Now, back to nucleic acids and their nitrogen bases. There are 2 types of nucleic acids, deoxyribonucleic acid and ribonucleic acid, both of which are found in the nucleus of cells.All nucleic acids are made up of nucleotides, which in turn are made up of the 3 sub-molecules mentioned earlier: pentose sugar (ribose for RNA and deoxyribose for DNA), phosphate, and a nitrogen base. There are 2 types of nitrogen bases, purines and pyrimidines.

Purines are made up of adenine and guanine, and have 2 rings. It is found in both DNA and RNA. A memory trick for purines is : Its got 2 be GAP. The 2 is to remind you that there are 2 rings and the letters G, A, P, stand for guanine, adenine, and purine.

Pyrimidines are made up of thymine, uracil, and cytosine and have only one ring.Cytosine is found in both DNA and RNA. Thymine in found in DNA only and Uracil is found in RNA only. A memory trick for pyrimidines is: CUT the pyramid.The letters C, U, T stand for cytosine, uracil, and thymine and the word 'pyramid' is to make you think of  'pyrimidine'.